I have been though this countless times. And I still do because bullies don't stop. But I am not affect because of some things I do to them to make them stop.
The three main things you can do are:
1) Ignore them ~ Just tell them you don't care and go about doing your business. They will lose interest and leave you alone
2) Taste of their own medicine ~ Don't be afraid to insult them too. As long as you don't start it, they can't get you in trouble. When they get embarassed they will respect you and leave you alone. ( Not most recommended. But it works in my school )
3) Last and first resort ~ Call me.
I hope that sheds some light on what to do in certain situations :)